Disconnect switch for electric power systems

ABSTRACT

A disconnect switch for electric power systems wherein a pair of switch blades are aligned axially in a contacting position when operative and pivotally connected to a pair of insulators at their noncontacting ends. Means are provided on each of the switch blades for preventing axial movement of the switch blades when they are axially aligned while permitting the blades to be pivoted out of contacting engagement.

United States Patent Inventor Fred H. Cole 1028 South Sierra Bonita Ave., Los Angeles, Calif. 90019 Appl. No. 100,127 Filed Dec. 21, 1970 Patented Jan. 11, 1972 DISCONNECT SWITCH FOR ELECTRIC POWER SYSTEMS 8 Claims, 4 Drawing Figs.

US. Cl 200/48 lnt.Cl ..l-l0lh 31/00 Field of Search 200/48, 48

CE, 48 SB, 146, 144

[56] References Cited UNITED STATES PATENTS 2,835,756 5/1958 Bagnagatti 200/48 CB Primary Examiner-Herman J. Hohauser Att0rneyMellin, Moore & Weissenberger ABSTRACT: A disconnect switch for electric power systems wherein a pair ofswitch blades are aligned axially in a contacting position when operative and pivotally connected to a pair of insulators at their noncontacting ends. Means are provided on each of the switch blades for preventing axial movement of the switch blades when they are axially aligned while permitting the blades to be pivoted out of contacting engagement.

PATENJTED 41W 1 mm 31634534 INVENTOR FRED H. COLE Mv/y ATTORNEYS DISCONNECT SWITCH-FOR ELECTRIC POWER SYSTEMS BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to electric switches; and, more particularly, to means for preventing the accidental opening of a switch due to external forces.

2. Description of the Prior Art In high-current disconnect switches for electric power systems, axially aligned contacting switch blades are used to carry current therethrough. The current is supplied by a plurality of parallel wires connected to each of the blades. Should a short circuit occur in the system, these parallelly disposed wires tend to pull or squeeze together, thus creating unpredictable axial stresses which tend to pull the switch blades apart. Other external forces which may cause such axial stresses are high-velocity winds, seismic shocks such as earthquakes, etc., or a combination of the above. Any of these forces may be sufiicient to pull the switch blade heads out of contact, thus creating an electric arc which destroys the switch.

Conventional switches are designed with sufficiently strong parts to withstand these forces, but this design approach becomes more and more impractical as higher voltages require longer insulation and higher currents increase the stressing forces to the point where mechanical failure of the insulators and bending of the insulator supports becomes a real problem.

It is therefore necessary to provide means specially adapted to prevent the switch blades from coming out of axial engagement under axial load without stressing the insulators or actuating shafts which support the blades.

SUMMARY OF THE INVENTION It is an object of the invention to provide a disconnect switch for electric power systems which limits the axial movement of the switch blades of the switch to a predetermined amount.

It is a further object of this invention to provide apparatus for limiting the axial movement of a pair of axially aligned contacting switch blades while permitting the blades to be moved out of contacting engagement.

It is a still further object of this invention to provide means for preventing the blades of a switch from being forced open due to axial forces induced in cables and bus bar terminals associated with the switch when conducting heavy fault currents, or by forces resulting from high-velocity winds, seismic shocks, or a combination thereof.

These and other objects are preferably accomplished by providing a pair of switch blades which are aligned axially in a contacting position when operative and pivotally connected to a pair of insulators at their noncontacting ends for intentional disengagement. Means are provided on both of the switch blades for preventing axial movement of the switch blades when they are axially aligned while permitting the blades to be pivoted out of contacting engagement.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevation of a switch in accordance with the teachings of my invention; 1

FIG. 2 is a top plan view of the switch of FIG. 1, parts thereof being omitted for convenience of illustration;

FIG. 3 is a detailed view of a portion of the switch of FIG. 1; and

FIG. 4 is atop plan view of a portion of the detailed view of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of the drawing, a switch assembly is shown having a base 11 in the general form of a rail or the like. A pair of posts 12 and 13 extend upwardly from each end of base 1 1 and are secured thereto by any suitable means, such as bolts 14 or the like. A pair of vertically disposed insulators 15 and 16 are rotatably mounted on each post 12 and 13. An actuating rod 17 extends between the eccentric brackets (not shown) attached to the insulator assemblies at their junction with posts 12 and13. The actuating rod 17 and the eccentric brackets constitute conventional means for rotating insulators 15 and 16 in opposite directions as will be discussed further hereinbelow. Means for operating actuating rod 17 to pivotally open disconnect switches of this type are well known in the electrical art and thus no further description would appear to be necessary.

A pair of switch blades 18 and 19 which are preferably tubular in configuration are fixedly secured to insulator collars 20 and 21 at the top of the supporting insulators l5, 16. This may be conventionally accomplished by providing flanges 22 and 23 or the like fixedly secured at one end to collars 20 and 21, respectively, and at their other ends to blades 18 and 19, respectively, through suitable bolt and clamp means 24 and 25, respectively. Thus, as can be seen, as the insulator assemblies 15 and 16 are rotated in opposite directions, switch blades 18 and 19 are rotated in the manner shown in the dotted lines of FIG. 2 as will be discussed further hereinbelow.

Conventional terminals 26 and 27 are pivotally secured to the ends of blades 18 and 19, respectively, adjacent their point of attachment to collars 20 and 21, to receive power cables W. Pivotal connection therebetween is provided by conventional pintle mountings 28 and 29, which are coaxial with insulator assemblies 15, 16, respectively. Electrical contact between the blades 18 and 19 and the terminals 26 and 27 are made by means of contacts 30 described in US. Pat. No. 3,209,087. The particular configuration of terminals 26 and 27 and their connection to switch blades 18 and 19 forms no part of this invention, and any other conventional arrangement may be substituted.

The novel features of my invention will now be described. As can be seen in FIG. 1, the switch blades 18 and 19 are axially aligned when the switch is closed. As discussed hereinabove, it is important that means be provided to prevent blades 18 and 19 from being pulled axially apart due to overload and other forces, while permitting the blades to be freely rotated into and out of their axially aligned position.

Referring now to FIG. 3, a block 31 is secured to the end of switch blade 18 contacting blade 19. This block 31 includes a pair of upstanding flanges 32 and 33 or the like, turning inwardly at lips 34 and 35, respectively, forming an aperture or notch 36. As can be seen in a comparison of FIGS. 3 and 4, lip 34 on flange 32 preferably extends across flange 32 and extends only a short distance inwardly toward the center of notch 36. Lip 35 on flange 33, on the other hand, extends a considerable distance inwardly toward the center of notch 36 and is preferably generally trapezoidal in plan view with a pair of abutment members 37 and 38 formed on the smaller size of the trapezoidally shaped lip 35 to thereby form a generally arcuate groove 39 for reasons to be discussed further hereinbelow. Block 31 is fixedly secured to blade 18 by suitable bolt and clamp means 40.

A beam assembly 41 is clamped to the other switch blade 19 by means of suitable bolt and clamp means 42. Assembly 41 includes a beam member 43 extending first upwardly therefrom, then longitudinally generally parallel to blades 18 and 19 and spanning the center contact of blades 18 and 19. Beam member 43 carries a hook or locking pin 44 which engages the aperture or notch 36 of block 31, as shown, during the final closure of the switch blades 18 and 19.

The rotation of a pair of switch blades mounted on rotating insulators into axial alignment with each other is well-known in the electrical art. Briefly, the head of one blade, as for example, blade 18, is a simple rounded nose while the other blade, as, for example, blade 19, carries a conventional flared anticorona cap 45 (FIG. 3) with resilient fingers (not shown) disposed inside cap 45 and adapted to be engaged by the head of blade 18 when it is rotated into alignment with switch 19 as shown by the solid lines in FIG. 2. in that figure, the circle segment of radius a indicates the path of the head end of blade 18 during closure or opening of the switch. Likewise, the circle segment of radius b indicates the path of the blade-receiving fingers inside anticorona cap 45. The locking pin 44 carried by beam member 43 on blade 19 is displaced in mounting by the distance c from the ends of the blade-receiving fingers. When the contacting head on switch blade 18 moves into engagement with the resilient fingers within cap 45 and engages at the centerline of the switch, the locking pin 44 moves into the aperture or notch 36 of block 31 and is in position to limit the axial movement of blades 18 and 19 in either axial direction.

As can be seen in FIG. 3, the locking pin 44 does not touch any portion of the walls forming aperture or notch 36 (i.e., for example, the flanges 32 and 33 and lips 34 and 35) when in position therein, Thus, the positional tolerances of locking pin 44 are not critical, and although locking pin 44 prevents the.

imposition of substantial bending stresses on the insulators and 16 through axial movement of blades 18 and 19 caused by external forces, it does not interfere with the normal operation of the switch. If one of the blades does move axially away from the other, locking pin 44 moves into groove 39 and is retained therein by abutment members 37 and 38.

The exact position, configuration and location of the block 31 and locking pin 44 is a matter of choice. Thus, block 31 may be mounted on blade 19 while locking pin 44 may be mounted on blade 18. The block 31 and locking pin 44 may be top mounted on blades 18 and 19 as shown and described hereinabove or bottom or side mounted (not shown). Instead of the locking pin 44 shown in the drawings, any suitable means on one switch blade adapted to engage mating means on the other switch blade may be provided to permit the switch blades to be rotated into axial position as indicated while preventing axial movement thereof in one or both axial directions.

In summary, by operating actuating rod 17, the insulators are rotated, thus moving switch blades 18 and 19 into and out of contact. The head of switch blade 18 moves into flared spring contact in a male-female relationship with the resilient fingers on blade 19, as for example, about 3 inches into contact therewith. Any axial movement of sufficient magnitude to approach this 3-inch tolerance and thereby create the danger of formation of an electric arc to burn away a portion of the switch blade or blades before a circuit breaker can be opened, is prevented by the engagement of locking pin 44 in notch or aperture 36. It will be understood that the disconnect switch described herein is not intended to be opened while current is flowing therethrough. Any short circuit or transient current surge in the power system in which the switch is to be used not only tends to squeeze together and thereby shorten the parallel electric cables associated with the switch, but also tends to create unpredictable mechanical stresses both within and without the switch structure. The conventional operating mechanism of the switch as described hereinabove is sufficiently strong to resist any rotary or transverse stresses which tend to pull the switch open, but any longitudinal stress can effectively be controlled in practice only by the novel mechanism which is the subject of this invention.

1 claim as my invention:

1. A disconnect switch for an electric power system comprising:

a pair of axially aligned contacting switch blades, each of said blades being pivotally mounted at their noncontacting ends to an insulator; and axial movement preventing means associated with both of said switch blades and independent thereof for preventing axial movement of said switch blades when axially aligned while permitting said blades to be pivoted out of contacting engagement, said axial movement preventing means including a block having an aperture therein secured to one of the switch blades adjacent the point of contact of said blades, and locking means secured to the other of said switch blades adjacent the point of contact of said blades, said locking means being adapted to move into said aperture in a noncontiguous relationship when said blades are axially aligned and to move out of said aperture during nonalignment of said blades, the walls of said aperture preventing axial movement of said switch blades when said locking means is disposed therein.

2. The switch of claim 1 wherein said aperture is a notch formed by upstanding flanges on said block, and lip portions extending generally normal from said flanges and inwardly toward the center of said notch, the free end of said lip portion adjacent said switch blade having said locking means secured thereto having a groove formed therein extending generally normal to the longitudinal axis of said switch blades, said locking means including hook means thereon adapted to move into said groove and be retained therein when one of said switch blades is moved axially away from the other.

3. The switch of claim 1 including terminals pivotally attached to the noncontacting ends of each of said switch blades.

4. Apparatus for limiting axial movement of a pair of axially aligned contacting switch blades for carrying electric current therethrough comprising;

insulators pivotally attached to the noncontacting ends of each of said switch blades; and axial movement preventing means associated with both of said switch blades and independent thereof for preventing axial movement of said switch blades when axially aligned while permitting said blades to be pivoted out of contacting engagement, said axial movement preventing means including a block having an aperture therein secured to one of the switch blades adjacent the point of contact of said blades, and locking means secured to the other of said switch blades adjacent the point of contact of said blades, said locking means being adapted to move into said aperture in a noncontiguous relationship thereto when said blades are axially aligned and to move out of said aperture during nonalignment of said blades, the walls of said aperture preventing axial movement of said switch blades when said locking means is disposed therein.

5. The switch of claim 4 wherein said aperture is a notch formed by upstanding flanges on said block, and lip portions extending generally normal from said flanges and inwardly toward the center of said notch, the free end of said lip portion adjacent said switch blade having said locking means secured thereto having a groove formed therein extending generally normal to the longitudinal axis of said switch blades, said locking means including hook means thereon adapted to move into said groove and be retained therein when one of said switch blades is moved axially away from the other.

6. The switch of claim 4 including terminals pivotally attached to the noncontacting ends of each of said switch blades.

7. A disconnect switch for an electric power system comprising:

a pair of axially aligned contacting switch blades, each of said blades being pivotally mounted at their noncontacting ends to an insulator; and

axial movement preventing means associated with both of said switch blades for preventing axial movement of said switch blades when axially aligned while permitting said blades to be pivoted out of contacting engagement, said axial movement preventing means including a block having an aperture therein secured to one of the switch blades adjacent the point of contact of said blades, and locking means secured to the other of said switch blades adjacent the point of contact of said blades, said locking means being adapted to move into said aperture when said blades are axially aligned and to move out of said aperture during nonalignment of said blades, the walls of said aperture preventing axial movement of said switch blades when said locking means is disposed therein, said aperture being a notch fonned by upstanding flanges on said block, and lip portions extending generally normal aligned contacting switch blades carrying electric current therethrough comprising:

insulators pivotally attached to the noncontacting ends of each of said switch blades; and

axial movement preventing means associated with both of said switch blades for preventing axial movement of said switch blades when axially aligned while permitting said blades to be pivoted out of contacting engagement, said axial preventing means including a block having an aperture therein secured to one of the switch blades adjacent the point of contact of said blades, and locking means secured to the other of said switch blades adjacent the point of contact of said blades, said locking means being adapted to move into said aperture when said blades are axially aligned and to move out of said aperture during nonalignment of said blades, the walls of said aperture preventing axial movement of said switch blades when said locking means is disposed therein, and said aperture being a notch formed by upstanding flanges on said blocks, and lip portions extending generally nonnal from said flanges and inwardly toward the center of said notch, the free end of said lip portion adjacent said switch blade having said locking means secured thereto having a groove formed therein extending generally normal to the longitudinal axis of said switch blades, said locking means including hook means thereon adapted to move into said groove and be retained therein when one of said switch blades is moved axially away from the other.

i ii I 1 

1. A disconnect switch for an electric power system comprising: a pair of axially aligned contacting switch blades, each of said blades being pivotally mounted at their noncontacting ends to an insulator; and axial movement preventing means associated with both of said switch blades and independent thereof for preventing axial movement of said switch blades when axially aligned while permitting said blades to be pivoted out of contacting engagement, said axial movement preventing means including a block having an aperture therein secured to one of the switch blades adjacent the point of contact of said blades, and locking means secured to the other of said switch blades adjacent the point of contact of said blades, said locking means being adapted to move into said aperture in a noncontiguous relationship when said blades are axially aligned and to move out of said aperture during nonalignment of said blades, the walls of said aperture preventing axial movement of said switch blades when said locking means is disposed therein.
 2. The switch of claim 1 wherein said aperture is a notch formed by upstanding flanges on said block, and lip portions extending generally normal from said flanges and inwardly toward the center of said notch, the free end of said lip portion adjacent said switch blade having said locking means secured thereto having a groove formed therein extending generally normal to the longitudinal axis of said switch blades, said locking means including hook means thereon adapted to move into said groove and be retained therein when one of said switch blades is moved axially away from the other.
 3. The switch of claim 1 including terminals pivotally attached to the noncontacting ends of each of said switch blades.
 4. Apparatus for limiting axial movement of a pair of axially aligned contacting switch blades for carrying electric current therethrough comprising; insulators pivotally attached to the noncontacting ends of each of said switch blades; and axial movement preventing means associated with both of said switch blades and independent thereof for preventing axial movement of said switch blades when axially aligned while permitting said blades to be pivoted out of contacting engagement, said axial movement preventing means including a block having an aperture therein secured to one of the switch blades adjacent the point of contact of said blades, and locking means secured to the other of said switch blades adjacent the point of contact of said blades, said locking means being adapted to move into said aperture in a noncontiguous relationship thereto when said blades are axially aligned and to move out of said aperture during nonalignment of said blades, the walls of said aperture preventing axial movement of said switch blades when said locking means is disposed therein.
 5. The switch of claim 4 wherein said aperture is a notch formed by upstanding flanges on said block, and lip portions extending generally normal from said flanges and inwardly toward the center of said notch, the free end of said lip portion adjacent said switch blade having said locking means secured thereto having a groove formed therein extending generally normal to the longitudinal axis of said switch blades, said locking means including hook means thereon adapted to move into said groove and be retained therein when one of said switch blades is moved axially away from the other.
 6. The switch of claim 4 including terminals pivotally attached to the noncontacting ends of each of said switch blades.
 7. A disconnect switch for an electric power system comprising: a pair of axially aligned contacting switch blades, each of said blades being pivotally mounted at their noncontacting ends to an insulator; and axial movement preventing means associated with both of said switch blades for preventing aXial movement of said switch blades when axially aligned while permitting said blades to be pivoted out of contacting engagement, said axial movement preventing means including a block having an aperture therein secured to one of the switch blades adjacent the point of contact of said blades, and locking means secured to the other of said switch blades adjacent the point of contact of said blades, said locking means being adapted to move into said aperture when said blades are axially aligned and to move out of said aperture during nonalignment of said blades, the walls of said aperture preventing axial movement of said switch blades when said locking means is disposed therein, said aperture being a notch formed by upstanding flanges on said block, and lip portions extending generally normal from said flanges and inwardly toward the center of said notch, the free end of said lip portion adjacent said switch blade having said locking means secured thereto having a groove formed therein extending generally normal to the longitudinal axis of said switch blades, said locking means including hook means thereon adapted to move into said groove and be retained therein when one of said switch blades is moved axially away from the other.
 8. Apparatus for limiting axial movement of a pair of axially aligned contacting switch blades carrying electric current therethrough comprising: insulators pivotally attached to the noncontacting ends of each of said switch blades; and axial movement preventing means associated with both of said switch blades for preventing axial movement of said switch blades when axially aligned while permitting said blades to be pivoted out of contacting engagement, said axial preventing means including a block having an aperture therein secured to one of the switch blades adjacent the point of contact of said blades, and locking means secured to the other of said switch blades adjacent the point of contact of said blades, said locking means being adapted to move into said aperture when said blades are axially aligned and to move out of said aperture during nonalignment of said blades, the walls of said aperture preventing axial movement of said switch blades when said locking means is disposed therein, and said aperture being a notch formed by upstanding flanges on said blocks, and lip portions extending generally normal from said flanges and inwardly toward the center of said notch, the free end of said lip portion adjacent said switch blade having said locking means secured thereto having a groove formed therein extending generally normal to the longitudinal axis of said switch blades, said locking means including hook means thereon adapted to move into said groove and be retained therein when one of said switch blades is moved axially away from the other. 